The present invention relates to a method of and a system for processing an output signal of a throttle opening degree sensor.
In automatic transmissions, a degree of opening of an engine throttle valve is detected by a throttle opening degree sensor. In order to compensate for a possible error due to an inappropriate mounting of the throttle opening degree sensor and/or for a product-to-product variability in the throttle opening degree sensor, a predetermined correction of the output signal of the throttle opening degree sensor is conducted. According to Japanese Patent Application First (unexamined) Publication No. 63-180755, an idle switch is provided and a predetermined correction of the output signal of a throttle opening degree sensor is conducted based on the actual output signal generated by the throttle sensor when the idle switch is rendered ON. According to Japanese Utility Model Application First (unexamined) Publication No. 1-14445, it is recognized that the engine throttle valve is fully closed when the engine revolution speed continues to stay in a predetermined low speed range for a predetermined period of time, and the actual output signal of the throttle sensor generated under this condition is used to conduct a predetermined correction of the output signal of the throttle sensor.
These two proposals pose a problem when the throttle valve is varied rapidly. In the case where the idle switch is used, if the throttle opening degree is increased rapidly from the fully closed state, the output signal of the throttle sensor follows this change without any delay, but there occurs a delay until the idle switch is rendered OFF. Thus, there occurs a period of time where the idle switch stays ON although the throttle valve has already been opened. If the correction is conducted during this period of time, the correction of the output signal is deviated toward a greater throttle opening degree. In the case where the engine revolution speed is used, the engine revolution speed varies slowly in response to a rapid change in the throttle opening degree. Thus, the correction of the output signal of the throttle sensor is deviated toward a greater throttle opening degree if the correction is conducted during this transition period.
An object of the present invention is to solve the problem encounted in the previously mentioned proposals.